In the demonstration, overseen by engineers and technicians from Rossi's mysterious US customer, the device appeared to produce over 470 kilowatts of heat for several hours. The customer was evidently satisfied and paid for the device, though other scientists and journalists attending were not given close access to the test equipment.

Following his first sale, Rossi now says he has orders for thirteen more megawatt-class E-Cat power plants. He's offering them to anyone at $2,000 (£1,250) a kilowatt, which works out at $2 million (£1.25 million) per unit, and says he has customers in the US and Europe. Rossi says a domestic version rated at a few kilowatts is at least a year away. He is also working on adapting the E-Cat so its heat output can converted to electricity, but this will require higher working temperatures and will take two years or more.

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This is not quite what you'd expect from a fraudster.

Firstly, the demonstration should have been much more convincing. The shipping container housing the E-Cat setup should have been hoisted from a crane and visibly disconnected from any external power supply. As with all conjuring tricks, the audience should have been allowed to inspect the apparatus. And why only claim 470 kilowatts when you're supposed to be producing twice that amount? If the whole thing was set-up, and the mystery customer a fake, it was not well calculated to convince anyone else.

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Secondly, this is normally the point at which a con artist starts issuing shares, asking for capital, or taking "deposits" from gullible consumers. Anything to grab some cash from those willing to offer it. Instead, Rossi is apparently only taking orders from large customers who will be checking the devices work before they take delivery. These are people with good lawyers to write contracts and deal with any complications. They are not easy targets. Whatever he's doing, he's going for the longer game.

Meanwhile, the media coverage has been shifting away from the possibility of fraud, and some mainstream commentators are toying with the idea that this might just be the big breakthrough that Rossi claims.

It's a reasonable enough guess. The US Navy is one of the few institutions where cold fusion research still continues openly, but the evidence is scant. Although a Paul Swanson from SPAWAR was present as an observer at one test, this may simply be evidence of continuing interest in the field, and the organisation will not make any comment.

Then on 3 November MSNBC ran a cautiously optimistic piece under the headline "Italian cold fusion machine passes another test", noting that although there is widespread scepticism about cold fusion, "proof is adding up" that the technology works.

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More curious is the lack of a story from Associated Press. AP science reporter Peter Svensson flew from New York to attend the demonstration, and live coverage of the event was curtailed to give AP the exclusive. But Svensson has so far not written a word about it.

Some online commentators suggested that he had been silenced by "Chinese-style information censorship." When challenged, AP apparently initially tried to deny Svensson was there, though photographs suggest otherwise.

This led to a campaign encouraging people to contact Svensson about the story via his Twitter feed. At first he simply replied with variations of "Sorry, there's nothing I can tell you at this point", but later changed to "All I can say is 'stay tuned'".

Our guess is that AP does not want to publish anything until it can verify the reality and perhaps the identity of the customer. This in itself suggests a degree of optimism: it's gambling that there will be a big story at the end, and it has accepted being scooped by Fox and MSNBC on the smaller story of the demonstration in order to get it.

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Meanwhile, we're left waiting until Rossi delivers the next E-Cat, which will be going to a different customer, in a few months. Hopefully they will be less secretive. In fact, if interest keeps growing, they could put the machine on show and use the steam output to make froth on cups of cappuccino for paying spectators and get a quick return on their £1.25 million investment.